Electrical connector having rf filter



Aug. 10, 1965 V T. E. DAHLEN 3,200,355

ELECTRICAL CONNECTOR HAVING RF FILTER Filed Nov. 24. 1961 2 Sheets-Sheet1 Z /EODOQE E: Dfif/LEN I N VE N TOR.

United States Patent ELlEtZTRlCAL CUNNECTUR HAVING RF FILTER Theodore E.Dahlen, La Puente, Caiif., assignor, by mesne assignments, tointernational Telephone and Telegraph Corporation, New York, N .Y., acorporation of Maryland Filed Nov. 24, 1961, Ser. No. 154,807 6 (Zlaims.(Cl. 333-49) The present invention relates to electrical connectorswherein one or more contact terminals are mounted in one connectormember and complementary contact terminals are mounted in anotherconnector member, the cor1- tact terminals mating to provide one or moreelectrical circuits upon interengagement of the two connector members.The invention relates more particularly to such a multicontactelectrical connector wherein one or more RF filter elements comprisingeither a capacitor or an inductor, or both, are electrically coupledwith contact terminals of one of the connector members so as toattenuate or ground out unwanted RF signals which might otherwise passthrough the connector.

In many circuits it is necessary or desirable to include and RF filterwhich may include one or more capacitors, and which preferably alsoincludes at least one inductor, and it is frequently particularlydesirable to embody such RF filter components in an electrical connectorso that the circuit is not interrupted by the filter at any other point.For example, in vehicle electrical systems the embodying of RF filtercomponents in one or more electrical connectors eliminates the necessityfor a large amount of expensive shielding which would otherwise berequired.

However, because of the size limitations of electrical connectors, andalso because of the requirement that optimum electrical characteristicsmust be maintained in electrical connectors, it has heretofore presenteda very difficult problem to incorporate such RF filter components in anelectrical connector. Prior art attempts to produce electricalconnectors having one or more RF filter components therein have resultedin connectors which are particularly difficult to assemble and whereinneither the contact terminals nor the RF filter elements or componentscould be removed and replaced in the event of damaged parts or necessityto change the values of the filter components, or to reconstitute any ofthe circuits associated with the connector.

In view of these and other problems in the art, it is an object of thepresent invention to provide an electrical connector member having oneor more contact terminals mounted therein, and which embodies one ormore RF filter elements or components electrically coupled with each ofthe contact terminals so as to suppress or ground out unwanted RFsignals which may be applied to the terminals.

Another object of the present invention is to provide an electricalconnector of the character described wherein one of the connectormembers embodies one or more RF filter elements or componentselectrically associated with one or more contact terminals therein, andwherein the contact terminals and the RF filter elements are removableand replaceable in the connector member so that damaged parts can beremoved and replaced and the values of the filter elements or componentscan be changed.

Another object of the invention is to provide an electrical connectormember of the character described having one or more contact terminalsmounted therein, wherein at least one capacitor component is arranged soas to shunt RF signals from each contact terminal to a conducting shellof the connector so as to ground out RF signals which may be applied tothe contact terminals, and which may also include inductor meansassociated with each contact terminal so as to present a barrier to RFsignals which may be applied to the terminals.

A further object of the present invention is to provide an electricalconnector member of the character described having RF filter componentstherein, wherein the RF filter components are mounted on the individualcontact terminals, and these contact terminals are removably supportedin the body of the connector member, whereby the RF filter componentscan be replaced merely by removal and replacement of the contactterminals themselves.

It is an additional object of the invention to provide an electricalconnector member of the character described having RF filter components,wherein the filter components are primarily mounted in the body of theconnector member and are adapted to cooperate with contact terminalswhich are removably supported in the body of the connector member.

These and other objects and advantages of the invention will become moreapparent from a consideration of the description which follows taken inconjunction with the drawings.

In the drawings, FIG. 1 is an axial sectional view, partly in elevation,illustrating a presently preferred embodiment of the invention whereinthe RF filter elements or components are mounted on removable contactterminals.

FIG. 2 is a greatly enlarged fragmentary section of a part of FIG. 1,illustrating details of construction of one of the contact terminals andits mounting in the connector member.

FIG. 3 is a schematic diagram illustrating the RF electrical circuitassociated with the contact terminal shown in FIG. 2.

FIG. 4 is an enlarged fragmentary section showing a connector memberhaving an external shell similar to that of FIG. 1, but embodying analternative contact terminal and terminal supporting structure whereinthe RF filter components are primarily embodied in the body portion ofthe connector member.

FIG. 5 is an enlarged fragmentary sectional view illustrating a furtherembodiment of the invention which is a variation of the embodiment shownin FIG. 4.

Referring at first to FIGS. 1 and 2 of the drawings, a connector member10 is shown, and comprises the receptacle portion of an electricalconnector which also includes a mating plug portion (not shown). Theconnector member 10 includes a tubular outer metal shell 12 having arearward portion 14 and a forward skirt portion 16, with an inwardlydirected flange 18 between the portions 14 and 16.

A contact terminal supporting body 20 is removably mounted in therearward portion 14 of shell 12, being retained against forward movementin the shell by abutment of a forwardly facing shoulder 22 on the body20 against flange 18 in the shell. A rearwardly facing shoulder 24 onthe body 20 is engaged by a retainer 26 to prevent rearward movement ofbody 20 in the shell, the retainer 26 being fastened to the shell bymeans of screws 28.

The contact terminal supporting body 26 is made in two parts, a rearwardbody portion 39 composed of a conducting material and a forward bodyportion 32 composed of insulation material. The body portions 30 and 32may be bonded together as by means of a suitable bonding cement.Suitable conducting materials of which the rearward body portion 30 maybe composed, which are given by way of example only and not oflimitation, are solid metal, which may be die cast or machined, sinteredmetal, or a resin modified by inclusion of a powdered metallic filler soas to be conductive, such as diallyl phthalate embodying finely powderedcopper. The advantage of such a resin modified to be conductive is thatit can be molded much in the manner of an ordinary connector insulationbody.

The contact terminal supporting body has a plurality of terminalreceiving bores 34 extending therethrough from the rearward face 36 ofthe body 20 to the forward face 38 of body 20. Each of the bores 34 hasa generally cylindrical forward constricted portion 40 disposed in theforward insulation portion 32 of the body, and an enlarged rearwardportion 42, the bore including a rearwardly facing shoulder 44 betweenthe generally cylindrical forward portion 40 and the enlarged rearwardportion 42. Additionally, a constriction is provided at the rear end ofthe enlarged rearward portion 42 of the bore so as to present aforwardly facing shoulder 46.

A contact retention sleeve 48 is seated in the enlarged rearward portion42 of the bore, the sleeve 48 comprising a split spring sleeve memberthat can be contracted and inserted into the bore through the rear endthereof and then permitted to expand into position as best shown in FIG.2 so that its forward edge is abuttable against the rearwardly facingshoulder 44 to prevent forward movement of sleeve 48 and its rearwardedge is abuttable against the forwardly facing shoulder 46 to preventrearward movement of sleeve 48 in the bore. One or more spring retentionfingers 50 are struck inwardly from the wall of the contact retentionsleeve 48 so as to incline forwardly and radially inwardly. These springretention fingers 50 preferably are integrally joined with the body ofsleeve near the rear end of the sleeve. Additionally, one or more springcontacting fingers 52 are struck inwardly from the wall of the retentionsleeve 48 forwardly of the retention fingers 50. Electrical connectionis present from the contacting fingers 52 through the sleeve 48 andthrough the conducting rearward body portion to the outer metal shell12, so that when the outer shell 12 is grounded, the spring contactingfingers 52 will likewise be at ground potential.

The bores 34 extending through the terminal supporting body 20 areadapted to receive respective socket contact terminals 54. However, itis to be understood that the invention is equally applicable to pincontact terminals, or to any other type of terminal capable of matingwith an opposing terminal in another connector member, as for example ahermaphrodite type of terminal. Each of the socket contact terminals 54includes a generally cylindrical tubular forward socket portion 56 whichfits into the forward bore portion and is adapted to receive a matingpin, a reduced cylindrical intermediate portion 58, and a generallycylindrical tubular rearward portion 60 within which a conductor wiremay be soldered or crimped.

Mounted on the reduced cylindrical intermediate portion 58 of thecontact terminal 54 is an annular RF filter unit 62. This unit includesa generally cylindrical capacitor barrel 64 composed of conductingmaterial and which, like the conducting rearward body portion 30, may becomposed of solid or sintered metal or a resin that is modified to beconductive. If the conducting capacitor barrel 64 is of this modifiedconductive resin type, it can readily be molded in position about thereduced cylindrical portion 58 of the contact terminal. The barrel 64has a cylindrical inner wall 66 and a cylindrical outer wall 68, andincludes a forward surface 70 and a reduced rearward portion 72presenting a rearwardly facing shoulder 74.

An annular inductor bead 76 is disposed within the barrel 64 of RFfilter unit 62 intermediate the ends of the barrel 64, the inductor bead76 having a cylindrical inner surface 78. The inner surface 78 of head76 may either be in direct contact with the reduced cylindricalintermediate portion 58 of the contact terminal, or it may be slightlyspaced outwardly therefrom. Even if the head 76 is in direct contactwith the portion 58 of the terminal, the volume resistivity of the beadis so high that there is no substantial DC. leakage between the terminal54 and the barrel 64. Inductor bead 76 is composed of a ferromagneticmaterial having a suitable permeability. Ferrite is the presentlypreferred material for the inductor bead 76, this being a ceramicferromagnetic material. It is to be understood, however, that theinvention is not limited to the use of any particular type offerromagnetic material for the inductor bead 76.

A pair of dielectric sleeves $0 and 82 are disposed,

I respectively, rearwardly and forwardly of the inductor bead 76 betweenthe cylindrical intermediate portion 58 of the terminal and thecylindrical inner wall 66 of the barrel 64. Although any suitabledielectric material may be employed in the dielectric sleeves and 82, apresently preferred dielectric material is barium titanate, which has arelatively high dielectric constant. Examples of other materials whichcan be used are Teflon and nylon. Even an air gap could be employed asthe dielectric if desired.

Each end of the capacitor barrel 64 is electrically isolated from theadjacent opposed shoulder on the contact terminal 54 by a layer 83 ofinsulating material.

The RF filter unit 62 provides an RF circuit arrangement like thatillustrated diagrammatically in FIG. 3, which is a 1r type of filter.Thus, the contact terminal 54 is represented in FIG. 3 as a conductor84. Disposition of the inductor bead 76 about the reduced intermediateportion 58 of the terminal has the electrical effect of the inductor 86in the conductor 84 in FIG. 3. The gap defined by dielectric sleeve 80between the reduced intermediate portion 58 of the contact terminal andthe barrel 64 has the effect of the capacitor 88 shown in the diagram ofFIG. 3, while the similar gap defined by the dielectric sleeve 82 at theother side of the inductor head 76 has the electrical effect of thecapacitor 89 shown in the diagram of FIG. 3. Grounding of the capacitorsis effected by the electrical connection between the spring cont-actingfingers 52 of the retention sleeve 48 and the cylindrical outer wall 68of the capacitor barrel 64.

It is to be understood that the capacitance across each of thedielectric sleeves 80 and 82 can be varied by variation of the type ofdielectric material used, width of the dielectric gap, length of thedielectric gap, and diameter of the dielectric gap. Similarly, it is tobe understood that the amount of inductance of the inductor head 76 maybe varied by varying the composition of the ferromagnetic materialemployed therein, and by varying the size and configuration of the head.

The contact terminal 54 is removably mounted in the bore of thesupporting body 20 merely by insertion of the terminal into the borefrom the rearward end of the bore. 'For ward travel of the terminal inthe bore is limited by abutment of the forward surface 70 of barrel 64against the rearwardly facing shoulder 44 in the bore. As the contactterminal 54 is being inserted into the bore, the annular enlargementpresented by the barrel 64 will deflect the spring retention fingers 5toutwardly until the rearwardly facing shoulder 74 on the barrel 64passes the free ends of the fingers 50, at which time the fingers 50will spring back inwardly behind the shoulder 74 on the barrel 64 toreleasably lock the contact in its operative position in the bore. Inthis position, the spring contacting fingers 52 will be resilientlyengaged against the outer cylindrical wall 68 of the barrel 64 inelectrical contact therewith.

Removal of the contact terminal 54 from the bore is effected byinsertion of a suitable tool into the rear end of the bore so as todeflect the retention fingers 50 outwardly past the rearwardly facingshoulder 74 on the barrel 64, permitting manual withdrawal of thecontact from the bore.

This removable mounting of the contact terminals 54 in the bore permitsreplacement of one or more of the terminals for any desired reason, suchas in the event of damage to a terminal or to the parts, thereofeffecting the electrical characteristics of the RF filter unit, or forchanging the values of the capacitor or induct or components of one ormore of the RF filter units, or for re constituting one or more circuitsassociated with the connector.

FIG. 4 illustrates an alternative embodiment of the invent-ion whereinthe :RF filter unit is carried principally in the body of the connectormember rather than in the contact terminal itself. The connector body,designated generally by the numeral 90 in FIG. 4, may be mounted in anouter metal shell 91 generally similar to the shell 12 shown in FIG. 1.However, the shell 91 is shown as a plug shell rather than a receptacleshell as in FIG. 1.

The body 90 is made up principally of a series of plates which arebonded together as a unit, and including, from rear to front, a rearwardinsulator plate 92 a first conductive plate 94, an inductor plate 96, asecond conductive plate 98, and a forward insulator plate 100. Aplurality of parallel terminal receiving bores 102 extend through thebody 90 from its rearward face 104 to its forward face 106.

The rearward insulator plate 92 has an enlarged rear- Ward portion 108of each of the bores 102 therein, each bore presenting a rearwardlyfacing shoulder 110 at the forward end of the enlarged portion 108. Aninwardly directed lip is provided proximate the rear end of eachenlarged bore portion 108 presenting a forwardly facing shoulder 11-2. Acontact retention sleeve 114 comprising a split spring sleeve is engagedin the enlarged bore portion 108, and is prevented from moving forwardlyby the shoulder 110 and from moving rearwardly by the shoulder 112. Thecontact retention sleeve 114 has one or more spring retention fingers116 struck inwardly from the wall thereof so as to extend forwardly andradially inwardly from their connections with the body of the sleeve114.

The contact terminal 118 shown in FIG. 4 is again one of a plurality ofsocket contact terminals mounted in the respective bores 102, althoughit is to be understood that a pin contact terminal or any other desiredtype of terminal may be employed. The contact terminal 118 has anelongated body portion 120 of general- 1y cylindrical externalconfiguration which is disposed primarily in the portion of the bore 102which extends through the plates 94, 96, 98 and 100, and this elongatedIbody portion 120 has a tubular forward socket portion 122 adapted toreceive a mating pin. The contact terminal 118 includes an annularcollar 124 immediately to the rear of the elongated body portion 120,and the rearward end of contact terminal 113 comprises a tubular portion126 within which a wire conductor may be soldered or crimped.

The contact terminal 118 is engaged in the bore 102 by insertion fromthe rear end thereof, and the forward limit of travel of the terminal118 is defined by engagement of the annular collar 124 against therearwardly facing shoulder 110 in the bore. During insertion of thecontact terminal 118 into the bore, the annular collar 124 deflects thespring retention fingers 116 radially outward- =ly until the collar 124is in front of the free ends of the spring fingers 116, at which timethe fingers 116 snap radially inwardly behind the collar 124 toreleasably lock the terminal in its operative position as shown in FIG.4. The terminal may then be removed by insertion of a suitable tool intothe rear end of the bore so as to deflect the fingers 116 radiallyoutwardly past the outer extremity of the annular collar 124, whichpermits extraction of the contact terminal from the rear end of thebore.

The conductive plates 94 and 98 may be die cast or machined of metal, ormay comprise sintered metal or a resin modified to be conductive, suchas the aforesaid diallyl phthalate which includes finely powderedmetallic filler, and the outer peripheries of these conductive plates 694 and 98 are electrically contacted to the metallic outer shell bymeans of a suitable annular contacting spring 128.

The inductor plate 96 is composed of a suitable ferromagnetic materialhaving the desired permeability, as for example a ferrite composition.The volume resistivity of inductor plate 96 is so high that there issubstantially no D'.C. leakage between the terminal 118 and either ofthe conductive plates 94 and 98, even if the inductor plate 96 were totouch the terminal.

The portion of the bore 102 lying within the first conductive plate 94is lined with a dielectric sleeve 130, while the portion of bore 102within the second conductive plate 98 is lined with a dielectric sleeve132, the dielectric sleeves 130 and 132 being composed of any suitabledielectric material having the desired dielectric characteristics, asfor example barium titanate, Teflon, nylon, or if desired simply an airgap.

The structure shown in FIG. 4 provides a 1r type of RF filter similar tothe structure of FIGS. 1 and 2, as diagrammatically illustrated in FIG.3. Thus, the contact terminal 118 is represented by the conductor 84 inFIG. 3, and the portion of the inductor plate 96 immediately surroundingthe contact terminal functions as the inductor 86 of FIG. 3. The gapdefined by dielectric sleeve 130 between the contact terminal 118 andthe bore portion which extends through the first conductive plate 94 isrepresented by the capacitor 88 in FIG. 3, while similarly the gapdefined by dielectric sleeve 132 between the contact terminal 118 andthe bore portion within the second conductive plate 98 is represented bythe capacitor 89 in FIG. 3.

The structure shown in FIG. 5 is similar to that of FIG. 4, with theexception that the inductor plate 96 of FIG. 4 has been replaced in FIG.5 by an insulator plate 134 which supports a plurality of inductor beads136 in annularly disposed relationship about the respective contactterminals 118, with an inner cylindrical surface 138 of each inductorbead 136 defining a portion of the respective bore 102. By thusemploying a separate inductor bead 136 in the insulator plate 134proximate each of the bores 102, there can be no possible inductivecoupling between adjacent contact terminals supported in the body 90.Although a small amount of such inductive coupling might sometimes bepresent where the unitary inductor plate 96 is employed as in FIG. 4,with all of the bores 102 extending through the single plate 96,normally such inductive coupling will not be sufficient to interferewith satisfactory operation of the connector.

While the instant invention has been shown and described herein in whatare conceived to be the most practical and preferred embodiments, it isrecognized that departures may be made therefrom within the scope of theinvention, which is therefore not to be limited to the details disclosedherein, but is to be accorded the full scope of the claims so as toembrace any and all equivalent devices.

I claim:

1. An electrical connector and filter assembly comprising a body memberhaving a conductive outer portion and having a bore extendingtherethrough, a contact terminal slidably mounted in said bore andadapted to be separably connected to a mating terminal in a second body,an electrically conducting capacitor member mounted on said contactterminal in encircling relationship to a portion thereof, electricallyinsulated therefrom and having a surface spaced from an opposed surfaceof said terminal to define a capacitor gap therewith, inductor meanscomposed of ferromagnetic material mounted on said terminal inencircling relationship to a portion thereof, electrically conductingspring means supported on one of said members and releasably engagingthe other member to releasably lock said terminal in said bore, saidspring means conductively engaging said capacitor member and beingelectrically connected to said conductive outer portion of said bodymember whereby upon release of said spring means said terminal,capacitor member and inductor means may be removed as a filter unit fromsaid body.

2.'An electrical connector and filter assembly as defined in claim 1wherein said spring means is mounted on said body member in said bore toprovide a ground connection and releasably engages a shoulder on saidcapacitor member.

3. An electrical connector and filter assembly as defined in claim 1wherein said capacitor member is provided with a second surface, axiallyspaced from said firstnamed surface and opposed to a surface of saidterminal to define a second capacitor gap therebetween, said inductormeans being disposed between said two capacitor gaps so as to define api filter.

4. An electrical connector and filter assembly as defined in claim 2wherein said capacitor member comprises a unitary sleeve, said inductormeans comprising an annular ring seated in the inner periphery of saidsleeve.

5. An electrical connector and filter assembly as defined in claim 1wherein the space between said opposed surfaces is occupied by a soliddielectric material of high dielectric constant and low loss, such asBaTiO and said ferromagnetic material is ferrite.

6. An electric connector and filter assembly as defined in claim 1including a dielectric sleeve between said opposed surfaces to providecapacitance reactance.

References Cited by the Examiner UNITED STATES PATENTS 2,383,890 8/45Robinson 33379 2,403,252 7/46 Wheeler 333--33 2,548,881 4/51 Ferrill33381 2,549,424 4/51 Carlson 333-79 2,569,667 10/51 Harvey et al 333-792,667,622 1/54 Weber et a1 33381 2,779,002 1/57 Foster et al 333813,002,166 9/61 Weinschel 33381 3,005,967 10/61 Weinschel 3338l HERMANKARL SAALBACH, Primary Examiner.

1. AN ELECTRICAL CONNECTOR AND FILTER ASSEMBLY COMPRISING A BODY MEMBERHAVING A CONDUCTIVE OUTER PORTION AND HAVING A BORE EXTENDINGTHERETHROUGH, A CONTACT TERMINAL SLIDABLY MOUNTED IN SAID BORE ANDADAPTED TO BE SEPARABLY CONNECTED TO A MATING TERMINAL IN A SECOND BODY,AN ELECTRICALLY CONDUCTING CAPACITOR MEMBER MOUNTED ON SAID CONTACTTERMINAL IN ENCIRCLING RELATIONSHIP TO A PORTION THEREOF, ELECTRICALLYINSULATED THEREFROM AND HAVING A SURFACE SPACED FROM AN OPPOSED SURFACEOF SAID TERMINAL TO DEFINE A CAPACITOR GAP THEREWITH, INDUCTOR MEANSCOMPOSED OF FERROMAGNETIC MATERIAL MOUNTED ON SAID TERMINAL